If I can't find the relevant Italian patent, I generally feature UK patents for Campagnolo gears. However this particular patent does not seem to have made it to these shores - so here is the French version.

It is rather similar to Campagnolo's original 1950 patent for the Campagnolo Gran Sport. However the 1950 patent depicts a very early (and now very rare) Gran Sport with 'large' Allen bolts, drilled pulley wheels etc.. This, 1953, patent depicts the classic, much more common, 1953 Gran Sport, with small allen bolts, solid pulleys, a cable adjuster etc.. Note that the p-spring cover cup is drawn as being very shallow. In early 1953 it was 3.5mm (much as shown here) but in late 1953 it was deepened to 5mm. This is the kind of stuff that Campagnolo geeks love.

• Publisher: L’Institut national de la propriété industrielle
• Inventor: Tullio Campagnolo
• Country: France
• Date: Priority date July 1953
• Derailleur brands: Campagnolo
• Derailleurs: Campagnolo Gran Sport (1012)